Intestinal trefoil factor (“ITF”) expression vectors and methods of overexpressing ITF have been described (see, for example, Thim et al., Biochemistry, 34:4757-4764, 1995, and Kanai et al., Proc. Natl. Acad. Sci. USA, 95:178-182, 1998). One useful expression system involves the use of the yeast Pichia pastoris, which allows overexpression and secretion of heterologous genes at high levels (see, for example, Tschopp et al., Bio/Technology, 5:1305-1308, 1987, and Cregg et al., Bio/Technology, 11:905-910, 1993).
A need exists in the art for new methods of producing ITF in quantity, especially without extraneous amino acid sequences (FIGS. 1-2). The present invention provides such vectors and methods.